A stud refers to a part of a shoe adapted to provide friction during play of sports and has a ground-engaging part. Thus, shoes for use in football tend to have relatively sharp and pointed sole studs and golf shoes have several relatively soft and blunt traction studs. As to the footwear with replaceable wear-resistant components, they tend to have relatively round sole studs to decrease resistance and wear from engagement with ground during moving and to avoid damaging the ground and the floor. The studs can be detachably assembled to the sole of an article of footwear by a bolt on the stud connected to a corresponding threaded socket to form or to be provided securely on the sole.
A threaded connection should be designed to be able to ensure the stud remains in place without accidental detachment even when a great force is applied. In the existing arts, studs have single-start or multi-start screw threads, of which the single-start screw thread is the simplest form and, when unscrewed, has greater resistance than multi-start screw thread, also provides a strong connection after multi-turn rotation of the bolt and the threaded socket. However, regardless of single-start or multi-start screw threads, both the stud and the threaded socket incorporate a locking ratchet to prevent the stud from accidental unscrewing, typically by providing a toothed element on both the stud and the threaded socket to allow the stud and the threaded socket to be mutually engaged when the former is inserted in the latter; said toothed elements are configured to allow the stud, when it is fully inserted, to be at any of the positions relative to the threaded socket.
Taiwan's patent No. 80202035—“Socket for Studded Footwear” is a design of improvement with double-start screw-thread instead of previously corresponding meshed teeth to prevent the stud from becoming off.
Taiwan's patent No. 90128130—“Studded Footwear” is a design with meshing structure at bottom working with threaded components to prevent the stud from becoming off.
Taiwan's patent No. 92108164—“Studded Footwear” is a design using threaded components with anti-reverse, locking accessory ribs to prevent the stud from becoming off.
Taiwan's patent No. 92108165—“Studded Footwear” is a design employing the locking effect of frictional components to prevent the stud from becoming off.
Taiwan's patent No. 97200043—“Shoe spike seat structure” is a design employing the locking effect of anti-reverse positioning block to prevent the stud from becoming off.
But, none of the above-listed inventions has disclosed a method for securing the studs by employing the effect of inertia.
Hence, in some motions where greater forces are applied to the studs, e.g., lateral forces or those as a result of fast and forward acceleration of the shoe wearer, as a method for securing the studs, it will be more effective by employing the effect of inertia, and unscrewing and changing studs will be made easier.